230 



TWENTY-NINTH FRUIT-GROWERS' CONVENTION. 



vation, without any artificial means being employed to keep up the 

 supply, soon reduces the supply of humus to a minimum, if it does not 

 exhaust it completely. This is shown by the soil becoming compact and 

 lifeless, by its inability to retain moisture, and by its refusal to absorb 

 water when applied. We frequently see irrigation in operation in 

 orchards where the water running out at the lower end of the furrow is 

 about equal in quantity to that started in at the upper end, and where 

 very frequent irrigations were absolutely necessary. But with a good 

 soil, properly treated, irrigation once "in two weeks is amply sufficient. 

 I believe that humus, through its mechanical action on the soil, and its 

 chemical action, through the processes that create it, on the mineral 

 fertilizing elements, is equal in value to any if not all of the others. 

 How, then, can it be supplied ? By keeping the surface soil well mixed 

 with decaying vegetable matter; and this can be accomplished only in 

 two ways: by liberal applications of the refuse of stables and stock cor- 

 rals (and while this is not especially rich in nitrogen it is in nitrifying 

 bacteria), and by the growing and plowing-under of green crops. As 

 the supph^ of stable manure is very limited for the needs of us all, the 

 latter method is the only available means of securing the necessary 

 amount of soil fertilizer. The Eastern farmer has found that by a rota- 

 tion of crops he obtains much the best results, and at frequent intervals 

 he grows a crop of one of the leguminous plants. We can not practice 

 rotation with our orchards, but we can groAv green crops and plow them 

 under. While any crop will furnish humus, we can, by the selection 

 of proper varieties, seemingly grow nitrogen at the same time. It has 

 long been known that the plowing-in of a crop of clover or other legum- 

 inous plant materially enriches the land, as shown in succeeding crops; 

 but it is only recently that science has demonstrated that the legumes 

 have, through the agency of minute bacterial organisms in nodules 

 attached to their root systems, the ability to convert the nitrogen of the 

 air, as well as the soil gases, to their use in building up their structure 

 and, on decomposition, leaving this nitrogen in the soil in a more readily 

 available form for the use of other plants. How frequently we see, 

 under natural conditions, the decumbent leguminous plants interspersed 

 with the more stately, thus illustrating that in the vegetable kingdom, 

 as in the animal, the small plants were intended as food for the larger, 

 and thus we have myriads of roots working on the mineral elements 

 and leaving them decomposed as digested food. 



As we can not furnish moisture to grow green-manure plants in 

 summer, we must select varieties that grow well in winter. The bean 

 called cowpea, so much used in the Southern States for this purpose, 

 will not do here, as it is more susceptible to cold and wet than corn; 

 but it has made a fine growth with us in summer with only a scant 

 supply of moisture. The common field pea has been most generally 



